1. Background and overview of geosynthetic clay liners -- 2. Durability and lifetime of the geotextile fibers of geosynthetic clay liners -- 3. Mineralogy and engineering properties of Bentonite -- 4. Hydraulic conductivity of geosynthetic clay liners -- 5. Contaminant transport through GCL-based liner systems -- 6. Chemico-osmosis and solute transport through geosynthetic clay liners -- 7. Gas permeability of geosynthetic clay liners -- 8. Internal and interface shear strength of geosynthetic clay liners -- 9. Slope stability with geosynthetic clay liners -- 10. Hydrologic performance of final covers containing -- 11. Oxygen diffusion through geosynthetic clay liners -- 12. Field observations of GCL behaviour.